I’ve organized with the DSA the last few years, and I caucused for Ron Paul in 2008.

I promise you you will have zero success getting Claudia De-La Cruz (who I voted for and was on the ballot in VA) put on the DNC or RNC ballot.

So no, you can’t just get on a ballot as a candidate by showing up. You need to be a party loyalist and there are no independent parties that voters show up for.

Hell even “down ballot” have to stick to the party line.